OTHER BRANCHES OF MEDICINE. 27 



An art may be entirely empirical, and yet be perfect so far as it goes ; but no 

 unknown cases are provided for, no contingencies foreseen. It is in its adap- 

 tation to these, that the triumph of a scientific over an empirical art manifests 

 itself; and in proportion as, from the nature of the subjects embraced by it, a 

 greater or less variety of novel cases presents itself, in that proportion is its 

 superiority more evident. It was well observed by Lord Bacon, that "it is the 

 office and excellence of all sciences to shorten the long turnings and windings 

 of experience." The deficiency of higher or more comprehensive laws should 

 not prevent us from making cautious use of those we already possess ; and, 

 where the demands of mankind require that an art should be practised even 

 in its imperfect condition, we must be content with such means of satisfying 

 them as lie within our reach. Contentment, however, by no means involves 

 a tacit acquiescence in the infirmities of our condition ; and the man of noble 

 and elevated mind will not only aim at the perfection of his science, from that 

 abstract love of knowledge, which is, as Sir H. Davy has beautifully remarked, 

 "in its ultimate and perfect development, the love of infinite wisdom and un- 

 bounded power, or the love of God," but may also safely cherish the belief, that 

 every contribution which he makes to general laws will ultimately have its 

 practical bearing on the condition of humanity. 



5. In no department of inquiry is it more necessary to keep these princi- 

 ples in view, than in that which relates to the phenomena of Vitality. The 

 changes which characterize living beings, and which in their totality constitute 

 the Life of these, are as capable of being referred to general laws, expressive 

 of their uniform conditions, as are phenomena of any other kind. But there 

 are many causes which render the attainment of these laws so difficult, that at 

 present we cannot assign to Biology (a term which may be advantageously 

 employed for the science of Vital Action, including Physiology and Pathology), 

 a high rank amongst the sciences. Hence the rules of any arts which are 

 founded upon it, can be only in part regarded as possessing that certainty 

 which it is desirable they should have. Some there are, which are derived 

 from laws of such high generality, that we cannot imagine any cause which 

 can interfere with their application. For example, it is one of these facts of 

 universal application, that a large mixture of carbonic acid in the medium to 

 which the circulating fluid is exposed for aeration, is prejudicial to life ; and 

 an obvious rule thence follows. But it is not a fact of equal universality, that 

 a dose of a purgative medicine will induce increased action of the bowels ; for 

 there may be many conditions of the system in which this shall not occur. 

 The physician, in directing the ventilation of a room, would be guided by a 

 high scientific principle ; whilst in administering a medicine, he is working 

 upon an induction derived from a comparatively limited experience. 



6. The art which most directly springs out of the science of Physiology, is 

 that of Hygiene, which may be defined as a system of rules for the preserva- 

 tion of the body in health, deduced from the principles by which its actions 

 are governed. Were the science of Physiology perfect, the art would require 

 little skill for its practice; this, however, is far from being the case. Its rules 

 are at present founded, in great part, upon too limited an induction to deserve 

 the title of universal; and their operation is frequently interfered with by a 

 number of causes, of whose mode of action we are almost entirely ignorant. 

 Still much has been done, by calling public attention to those, of which the 

 general importance is acknowledged, in preserving the body in health by 

 removing the causes of disease ; as the increased value of human life, shown 

 by statistical returns, abundantly testifies. And the Physiologist can readily 

 point out many more, which have not yet received the attention that their 

 importance deserves. The term Hygiene is sometimes used to include the 

 art of restoring as well as preserving health, by the use of means not strictly 



